Gundimeda Usha, McNeill Thomas H, Barseghian Barsegh A, Tzeng William S, Rayudu David V, Cadenas Enrique, Gopalakrishna Rayudu
Department of Cell and Neurobiology, Keck School of Medicine, University of Southern California, Los Angeles, California, USA.
J Neurochem. 2015 Jan;132(1):70-84. doi: 10.1111/jnc.12964.
Axonal regeneration after injury to the CNS is hampered by myelin-derived inhibitors, such as Nogo-A. Natural products, such as green tea, which are neuroprotective and safe for long-term therapy, would complement ongoing various pharmacological approaches. In this study, using nerve growth factor-differentiated neuronal-like Neuroscreen-1 cells, we show that extremely low concentrations of unfractionated green tea polyphenol mixture (GTPP) and its active ingredient, epigallocatechin-3-gallate (EGCG), prevent both the neurite outgrowth-inhibiting activity and growth cone-collapsing activity of Nogo-66 (C-terminal domain of Nogo-A). Furthermore, a synergistic interaction was observed among GTPP constituents. This preventive effect was dependent on 67-kDa laminin receptor (67LR) to which EGCG binds with high affinity. The antioxidants N-acetylcysteine and cell-permeable catalase abolished this preventive effect of GTPP and EGCG, suggesting the involvement of sublethal levels of H2 O2 in this process. Accordingly, exogenous sublethal concentrations of H2 O2 , added as a bolus dose (5 μM) or more effectively through a steady-state generation (1-2 μM), mimicked GTPP in counteracting the action of Nogo-66. Exogenous H2 O2 mediated this action by bypassing the requirement of 67LR. Taken together, these results show for the first time that GTPP and EGCG, acting through 67LR and elevating intracellular sublethal levels of H2 O2 , inhibit the antineuritogenic action of Nogo-A. Currently, several agents are being evaluated for overcoming axonal growth inhibitors to promote functional recovery after stroke and spinal cord injury. Epigallocatechin-3-gallate (EGCG), present in green tea polyphenol mixture (GTPP), prevents antineuritogenic activity of Nogo-A, a myelin-derived axonal growth inhibitor. The preventive action of EGCG involves the cell-surface-associated 67-kDa laminin receptor and H2 O2 . GTPP may complement ongoing efforts to treat neuronal injuries.>
中枢神经系统损伤后的轴突再生受到髓磷脂衍生抑制剂（如Nogo-A）的阻碍。天然产物，如绿茶，具有神经保护作用且长期治疗安全，可补充目前正在进行的各种药理学方法。在本研究中，我们使用神经生长因子分化的神经元样Neuroscreen-1细胞，发现极低浓度的未分级绿茶多酚混合物（GTPP）及其活性成分表没食子儿茶素-3-没食子酸酯（EGCG）可同时抑制Nogo-66（Nogo-A的C末端结构域）的神经突生长抑制活性和生长锥塌陷活性。此外，还观察到GTPP成分之间的协同相互作用。这种预防作用依赖于EGCG高亲和力结合的67-kDa层粘连蛋白受体（67LR）。抗氧化剂N-乙酰半胱氨酸和细胞可渗透的过氧化氢酶消除了GTPP和EGCG的这种预防作用，表明在此过程中存在亚致死水平H2O2的参与。因此，以推注剂量（5 μM）添加或通过稳态生成更有效地添加（1-2 μM）的外源性亚致死浓度H2O2，在抵消Nogo-66的作用方面模拟了GTPP。外源性H2O2通过绕过对67LR的需求来介导这种作用。综上所述，这些结果首次表明，GTPP和EGCG通过67LR起作用并提高细胞内亚致死水平的H2O2，从而抑制Nogo-A的抗神经生成作用。目前，正在评估几种药物以克服轴突生长抑制剂，促进中风和脊髓损伤后的功能恢复。绿茶多酚混合物（GTPP）中存在的表没食子儿茶素-3-没食子酸酯（EGCG）可预防髓磷脂衍生的轴突生长抑制剂Nogo-A的抗神经生成活性。EGCG的预防作用涉及细胞表面相关的67-kDa层粘连蛋白受体和H2O2。GTPP可能补充目前治疗神经元损伤的努力。
